Destruction of allogeneic tumour cells by peritoneal macrophages.

The population of peritoneal macrophages from mice immunised with allogeneic tumor cells contains two types of cytotoxic cell. One lyses the specific target cell, the other initiates activation of macrophages and hence leads to inhibition of growth of the specific target cell. The yield of lytic effector macrophages was found to depend on the route and the nature of the cell used for immunisation and the condition of the mice. The yield correlated with the yield of complement-dependent cytotoxic antibodies. In contrast, production of specific "activator" macrophages did not depend critically on these factors. The results underline the difference between the two types of cell and suggest that they are produced independently of one another.